Is the 3a cement mixer two different castings?

[DrJeep]

This isn't a new idea - in the 3a listing, Nick says:

The body was soon altered when the handle was removed from the engine cover, Several other minor alterations were done at the same time, The A frame that runs up from the wheels to the end of the mixer arm originally had a 4mm gap at the top, This was reduced to 3mm. Also the front mixer arm post which had a rounded top was altered to a squared off top. There are several other minor alterations and it is possible that the second body type was actually a completely new casting.

Hugh's new 1b with 3a wheels made me look more closely at the two 3a cement mixers I own. I've had the one on the left for at least 40 years, and it's the first time I'd ever noticed that one wheel is fitted the wrong way round. This must have been an easy error to make as the wheels are only painted on one side, so this one must have been upside down in the paint shop.

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But looking at this picture, and the other side too, it's apparent that there are lots of quite significant changes.

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I'd like to suggest that it's actually a whole new casting of the body, the barrel and the arm. Here's why:

body: there are well-documented changes, including removing the handle from the back of the mixer. But look at the rivets along the bottom of the engine cover. On the later 3a, they're smaller and further from the bottom. The lip at the back of the engine housing is also much bigger on the later model on the right. This could be the result of enlarging the mould, of course. But there's also a difference in the shape of the access panel below the vents - it's shorter and wider on the newer model. There are lots of other differences too, particularly in the chassis (note that my old one is broken at the top).

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barrel: The later barrel is nearly 1 mm longer. You can see this in the shape of the top, which becomes more parallel in the barrel on the right.

arm: Apart from the well-recorded differences in the handle, the lettering has changed sides. That's really only possible with a new moulding.

So what do you think? Obviously it's far too late to suggest that these should be 3a and 3b, but I think there are so many differences that they are the result of a completely new set of moulds. What do you think?

[Idris]

That there are two significantly different castings both for the body and the arm is beyond dispute (see also Nick's catalogue [page). The question is, what, if anything, to do about it.
The fact that there are two major components, each of which was subject to major revision, so making theoretically four (but in practice only three) significantly different models is a complicating factor. However, if we look at e.g. the 46b pantechnicon, there is no doubt whatsoever that the tooling underwent a major overhaul partway through production, yet it is a single model code. The same holds true for the 69a, but the 17a and 17b are treated as different models. However, Nick employs identical codes for the RW and SF versions of the same issue.
As Glenn suggests, it's probably a bit late in the day to start trying to rearrange the model codes, but I do think that Maurice A. Hammond in his book "Lesney Matchbox 1-75 Series Diecasts" was on to something with his double-letter coding (although the way he treated colours was highly inconsistent). So, for instance, what we call 17a and 17b, he would have called 17a and 17aa instead - clearly showing that they're basically the same model, but with retooling. On the other hand, he draws a distinction between the RW and SF versions of a particular issue, giving them different letter designations, thereby giving rise to the interesting question of when a casting difference is significant enough to warrant the model being seen as a new issue and so receiving a new letter suffix.
However, even if we were to embrace some kind of sub-division of letter suffixes, that would still leave the 3a out in the cold: body 1/arm 1 would be 3a, body 2/arm 2 would be 3aa, but how would you catalogue the hybrid body 2/arm 1 variation?

[DrJeep]

That there are two significantly different castings both for the body and the arm is beyond dispute

and the barrel too, though there are cross-over versions including all three components.

You're right: the existence of these cross-over versions is probably the best reason for the 3a to be catalogued as a single model, because the parts are basically interchangeable. I find it interesting that the second model is a completely new casting of every component, rather than being the result of a modified mould. This contrasts with the 9a and 9b, where the existing mould was modified with a new bumper, grille detail and additional lettering but has always been seen as a separate model. Perhaps the closest equivalent is the 4a and 4b Massey Harris, where the body, wheels and driver all changed but the two models remain very similar. The 4a and 4b certainly deserve their separate codes, but the changes aren't that different from those on the single-code 3a.

If only the second version had been a contrasting colour - my later 3a is a brighter blue (also discussed here) but not different enough to be exciting to most collectors!

[MatchboxFreak]

Could some of these differences be due to being cast in a mould which produced two parts at once?
The bow/arm for the barrel may have been produced as a left and a right casting which were mirror images of each other except the word “England“ was on the top half of the mould and the “Lesney” was on the bottom half of the mould (or visa versa).

The difference in the engine cover access door seems more deliberate than an accidental difference between two halves of a mould.

[Idris]

Could some of these differences be due to being cast in a mould which produced two parts at once?

Isn't the 3a too early for paired castings?

[DrJeep]

Could some of these differences be due to being cast in a mould which produced two parts at once?

Isn't the 3a too early for paired castings?

It's an interesting idea but I think that as Hugh says, it's too early for paired castings. There's quite a lot of evidence that these followed each other - perhaps the axles are the most obvious sign. My early one on the left has flat head axles; these aren't recorded on body 2. Body 1 isn't reported with arm 2, so I think these are definitely sequential rather than paired.

Thinking about this some more, I realised that the 7a milk float also has two different body castings, with the milk crates in a different position on the second body.